In this study, we performed low-temperature de Haas–van Alphen effect measurements on a Ce 1-xNd xCoIn 5 series, for x = 0.02 , 0.05, 0.1, and 1, down to T = 40 mK using torque magnetometry in magnetic fields up to 35 T. Our results indicate that a Fermi surface (FS) reconstruction occurs from a quasi-two-dimensional topology for Nd-2% to a rather three-dimensional one for Nd-5% , thus reducing the possibility of perfect FS nesting. The FS evolves further with increasing Nd content with no observed divergence of the effective mass between Nd-2% and 10%, consistent with the crossing of a spin density wave type of quantum critical point. Lastly, our results elucidate the origin of the Q phase observed at the 5% Nd-doping level [Raymond et al., J. Phys. Soc. Jpn. 83, 013707 (2014)].

The London penetration depth, λ(T), was measured in single crystals of Ce 1-xR xCoIn 5, R=La, Nd and Yb down to T min ≈ 50 mK (T c/T min ~50) using a tunnel-diode resonator. In the cleanest samples Δλ(T) is best described by the power law, Δλ(T) ∝ T n, with n ~ 1, consistent with line nodes. Substitutions of Ce with La, Nd and Yb lead to similar monotonic suppressions of T c, however the effects on Δλ(T) differ. While La and Nd dopings lead to increase of the exponent n and saturation at n ~ 2, as expectedmore » for a dirty nodal superconductor, Yb doping leads to n > 3, suggesting a change from nodal to nodeless superconductivity. As a result, this superconducting gap structure change happen in the same doping range where changes of the Fermi surface topology were reported, implying that the nodal structure and Fermi surface topology are closely linked.« less

Here, we study the behavior of the pseudogap in overdoped Bi 2Sr 2CaCu 2O 8+δ by electronic Raman scattering (ERS) and angle-resolved photoemission spectroscopy (ARPES) on the same single crystals. Using both techniques we find that, unlike the superconducting gap, the pseudogap related to the antibonding band vanishes above the critical doping p c = 0.22 . Concomitantly, we show from ARPES measurements that the Fermi surface of the antibonding band is holelike below p c and becomes electronlike above p c. This reveals that the existence of the pseudogap depends on the Fermi surface topology in Bi 2Sr 2CaCumore »2O 8+δ, and more generally, puts strong constraint on theories of the pseudogap phase.« less

In this study, the thermal conductivity of heavy-fermion superconductor Ce 0.95Nd 0.05CoIn 5 was measured with a magnetic field rotating in the tetragonal a-b plane. The thermal conductivity exhibits a step within the high-field low-temperature (HFLT) phase, which exists above 8 Tesla within the superconducting state, when field is rotated through the antinodal [100] direction of the superconducting d-wave order parameter. This anomaly indicates the presence of a third order parameter within the HFLT phase, similar to that of pure CeCoIn 5. Therefore, the HFLT state with triply intertwined orders, i.e., superconducting d-wave, magnetic spin-density wave (SDW), and a putativemore » superconducting p-wave pair-density wave (PDW), is robust against 5% Nd doping. The second magnetic phase within the superconducting state below 8 Tesla, a low-field SDW, displays a hysteresis in thermal conductivity as a function of field magnitude, which is also revealing the existence of a third order consistent with a p-wave PDW. Lastly, given different origins and properties of the HFLT and low-field SDW states, the presence of three intertwined orders in both phases is remarkable and of far-reaching consequences.« less

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